The present invention relates to a digital data processing apparatus for processing fixed-point data and floating-point data and, more particularly, to a fixed-point data/floating-point data converting apparatus.
Conventionally, conversion of this type is performed by a combination of microprograms or user commands. According to the conventional conversion operation, the shifting of fixed-point data, by one digit position to the left, and zero detection of the digit data to be shifted out are repeated. The number of continuous "zero" digits from the MSB of the fixed-point data (i.e., the number of leading "zero" digits) is thus obtained. An operation designated by software is performed by an ALU (arithmetic and logic unit) in accordance with the number of leading "zero" digits, thereby sequentially obtaining a mantissa part and an exponent part of floating-point data. By using the mantissa and exponent parts, normalized fixed-point data may be obtained.
However, according to the conventional converting means for obtaining fixed-point data by software, the shifting of digit position and zero detection must be performed repeatedly to determine the number of leading "zero" digits. The locations of the mantissa and exponent parts must be adjusted. For this reason, it is very difficult to convert fixed-point data to floating-point data, at a high rate of speed.